A Beginner’s Guide to Fixed Weir Plates

Successfully managing open channel flow is dependent on having the right primary device. Although there are several options from which to choose, one of the best is a fixed weir plate. Here are a few fixed weir plate facts that you should keep in mind when you’re shopping for a primary device for your flow management operation.

What Is a Fixed Weir Plate?

A fixed weir plate is a simple flow management device that you can use to measure the flow in an open channel. When you install a weir plate in an open channel, you obstruct the flow and then force it to flow over the weir crest, which is a small opening at the top of the weir plate.

As it passes over the weir plate, the flow is accelerated, and this acceleration is what allows your operator to measure the flow rate. When a weir is installed correctly, you should have no problem taking accurate flow measurements. Before you install a weir plate in your system, however, there are a few factors that you should keep in mind.

Choosing Weir Plate Materials

If you’re interested in using a weir for open channel flow management, the first factor you need to consider is what material your weir plate will be constructed from. For a weir to work correctly, the crest must not be damaged in any way. If the crest is damaged, flow will not be able to spill over it freely, which means it will not accelerate correctly.

To make sure that your weir plate works the way that you need, it is crucial that both the plate and the crest are constructed using a highly durable material. While stainless steel can be a good choice, fiberglass is usually the best option. Fiberglass is resistant to multiple forms of environmental damage and is very long lasting, which means your weir will function correctly well into the future.

Limitations to Keep in Mind

While researching fixed weir plate facts, it’s important to learn about some of the limitations of this popular device. In some applications, a weir plate isn’t the right choice, so if you install this device, it may result in inaccurate readings.

The biggest limitation of a weir plate is that it cannot measure flow from a pressurized pipe, but this is true of all open channel flow devices. Weirs can measure flow from a pipe if the flow isn’t pressurized, but you will need to add flow conditioners, which can increase your expenses.

Weirs are also very vulnerable to flows that contain solid waste, trash or biological matters. All of these items can accumulate in the weir crest and eventually block the flow completely.  

Purchase a Flow Device

Now that you know some important fixed weir plate facts, you should be able to decide if this device is right for your operation. If you need an open channel flow device such as a weir, Tracom, FRP can help you.

Tracom offers a wide array of flow management products constructed from fiberglass, and we can help you decide which is right for your system. Contact us today to get started.